1. Field of the Invention
The present invention relates to apparatus and method of assembling heat exchanging tube for a heat exchanger capable of automatically assembling heat exchanging tubes, which serve as heating tubes, cooling tubes or the like, applied to a heat exchanger (for example, a feed water heater, a boiler, a humidity separating and heating unit, a ground steam evaporator, and a cooling unit for cooling cooling water, condensed water, oil or the like) which is provided with thermal power generation plants, nuclear power generation plants and the like as an accessory.
2. Description of the Related Art
An example of a prior art will be first described with reference to FIG. 19 and FIG. 20. This example relates to an assembly of heat exchanging tubes as heating tubes in a horizontal type feed water heater used in thermal power generation plants, nuclear power generation plants and the like.
FIG. 19 schematically shows how the tubes are assembled to the feed water heater. The feed water heater is generally composed of a cylindrical frame 1 in which accommodated are a multiplicity of U-shaped tubes 2 called heating tubes into which circulating water flows and a tube bundle is formed by the tubes. The respective tubes 2 are assembled by being inserted into the holes 4 of a plurality of partitions 3 disposed in parallel with each other from an open end side with the U-shaped curved portions of the tubes 2 on a bent end side directed longitudinally.
As shown in FIG. 19, the tubes 2 are assembled in such a manner that the base portion 1a of the cylindrical frame 1 is fixed on a height adjustment table 5 as well as the partitions 3 are positioned at a predetermined height by supporters 6 and the tubes 2 are sequentially inserted into the holes 4 of the partitions 3 by the hand work of five to eight workers. After all the tubes 2 are inserted into the holes 4 of the partitions 3, a cylindrical frame 1b is combined with and welded to the base portion 1a of the feed water heater 1 to thereby complete a heat exchanger.
FIG. 20 shows a plan view of the partition 3 described above, FIG. 21 shows the state that the tubes 2 are inserted into the partitions 3 in an enlarged fashion and FIG. 22 shows a side surface shape of the tube 2. As shown in these drawings, the tube bundle is composed to 1000 to 3000 pieces of the tubes 2 in which the tube whose U-shaped curved portion on the bent end side has a minimum radius R is disposed at the center of the partition 3 and both the side portions of the tubes whose U-shaped curved portion has a larger radius R are sequentially disposed above and below the tube (CL in FIG. 21 shows a gap between a first stage and a third stage). In this case, since the tube 2 having a larger radius R covers the end portion of the tube 2 having a smaller radius R on the bent end side, the tube having the smaller radius R is inserted into the partitions 3 first and thereafter the tubes 2 having the larger radius R are sequentially assembled in a usual assembling process for inserting the tubes 2 from the open end side. Conventionally, an assembly job for assembling all the tubes 2 is regularly carried out from the tubes having the smaller radius R to the tubes having the larger radius R according to the above process.
An assembling method according to the above process will be described with reference to FIG. 19. In general, the tubes 2 are separately accommodated in a plurality of packing cases 7 after they are finished. Thus, all the packing cases 7 are piled up with the packing case 7 in which the tubes 2 whose U-shaped curved portion has a minimum radius R are accommodated disposed at an uppermost stage. Thereafter, each of the packing cases 7 is sequentially placed on a work table 8 in the order of the case located on an upper stage to the case located on a lower stage, a lid 7a on the upper surface of the packing case 7 is removed and then all the tubes 2 are lifted and taken out from the packing case 7 using a not shown crane, a hoist beam, a plurality of nylon strings and the like and placed on skids 9 placed on the packing case 7 and the dirt at the extreme ends of the tubes 2 are wiped out.
Thereafter, the five to eight workers lift up the tubes 2 on the skids 9 one by one and align the open ends of the tubes 2 with the holes 4 of the partition 3 and support and insert the tubes 2 while walking and the rearmost worker pushes the tube 2 until the bent end side thereof is fallen into the predetermined place of the partition 3. Before the rearmost worker finishes the pushing job, the foremost worker goes to a rear side and make preparation for the next job by taking up the next tube 2. Thereafter, the tubes 2 of the same radius R are sequentially assembled by the repetition of the above process.
On the completion of the insertion and assembly of the tubes 2 prepared on the skids 9, the tubes 2 of the same type are lifted by the crane, the lift beam, the nylon strings and the like and taken out onto the skids 9 again and the dirt at the extreme ends thereof are wiped out and thereafter jobs similar to the above jobs are carried out.
When the assembly of the tubes 2 having the minimum radius R to the first stage of the holes at the center of the partitions 3 is completed by the repetition of the above jobs, a necessary number of packing cases 7 which accommodate the tubes 2 corresponding to the second stages of the holes located above and below the first stage are prepared and the same jobs are repeated. Thereafter, a predetermined number of the tubes 2 are inserted into the holes 4 of the partitions 3 in the predetermined stages in the order of an odd stage and an even stage by the repetition of the same jobs. At that time, since a gap is necessary to take out the packing cases 7 accommodating the tubes 2 for respective stages, the tubes 2 for the odd stages and tubes 2 for the even stages are separately accommodated in the packing cases 7.
The tube 2 has a length of, for example, about 11 meters and is formed to a slender shape with a diameter D of about 20 millimeters. Thus, when there are a smaller number of support points, the job for inserting the tube 2 is difficult because the tube 2 is liable to be bent in such a case. Accordingly, there are conventionally required a large number of workers. Further, when the tubes 2 accommodated in the packing case 7 are taken out one by one, it is become difficult to take out the tubes 2 remaining in the packing case 7 because they collapse in the packing case 7. To cope with this problem, a necessary number of the tubes 2 must be previously taken out on the packing case 7, which requires an additional setup job before the insertion of the tubes.
The tubes 2 are regularly disposed in the feed water heater in the order of the tubes 2 having the minimum radius R to the tubes 2 having the maximum radius R as shown in FIGS. 20 to 22. However, since the tubes 2 must be sequentially inserted from the tubes 2 having a smaller radius R due to the characteristics of the U-shape as described above, a multiplicity of the packing cases 7 accommodating the tubes 2 of the same radius R must be prepared. When the tubes 2 having a different radius R are accommodated in the same packing case 7 to enhance the accommodating efficiency of the packing case 7, there arises a disadvantage that the tube 2 having, for example, a small radius is taken out from the packing case 7 in the midway of the above process and the opened packing case 7 must be moved to a different position and temporarily placed there. At the same time, since all the packing cases 7 in which the necessary tubes 2 are accommodated must be opened, a large space is required to temporarily place the opened packing cases.
Further, since the tubes 2 must be conveyed from the packing cases 7 disposed as described above to the work table 8, a job for lifting them by the crane or the like is increased as well as when the crane is used by other job, the tube conveying job must be interrupted. As described above, the assembly of the heat exchanging tubes in heat exchanger executed by the prior art method has various problems such that the tubes are inefficiently assembled because a large number of workers are required and many complicated manual jobs are necessary and the space in which the packing cases are disposed is increased.